Both x-rays and protons are used to bombard cancer cells during treatment, and they have the same cure rates. But new research shows that proton therapy has much lower risk of serious side effects compared with x-ray therapy.
According to the American Cancer Society, 1,762,450 new cases of cancer will be diagnosed in the U.S. this year. Over 600,000 people will die from cancer over the same period.
X-ray radiation is one of the most common therapies for cancer, but it is known to have a range of side effects. These can include fatigue, skin irritation, fever, nausea, vomiting, diarrhea, difficulty swallowing, and change in appetite.
A new study sought to find if proton therapy could possibly be a better option with fewer side effects.
The study was conducted by the Washington University School of Medicine in St. Louis, Missouri. Findings were presented at the American Society of Clinical Oncology meetings last month. Here is the full report. The team was led by Dr. Brian Baumann, a radiation oncologist at the school. He was also the lead author of the study.
The team examined almost 1,500 people with various forms of cancer. The patients were receiving a combination of chemotherapy and radiation therapy. Radiation is used if cancer has not spread to the rest of the body. The study compared the experiences of patients who received proton radiation therapy with those who received x-ray radiation therapy. The study focused on grade 3 side effects; these are severe enough to require hospitalization.
The study found the relative risk of severe side effects within 90 treatment days was two-thirds lower for people who received proton therapy compared to those who received x-ray therapy.
For the specific numbers — only 45 (11.5%) of the 391 patients who received proton therapy had a severe side effect within 90 days. For x-ray therapy patients the numbers were 301 of the 1,092 who received x-ray radiation (27.6%) had a severe side effect.
When looking at the two therapies, the study also did not find a statically relevant difference in survival rates between the two. So, while proton therapy is equally successful as a treatment, its rate of side effects is dramatically better than with x-ray therapy.
“While there have been other studies suggesting that proton therapy may have fewer side effects, we were somewhat surprised by the large magnitude of the benefit,” writes Dr. Baumann in the study.
Another benefit of using proton radiation compared to x-rays is precision. Proton therapy carries far less risk of damaging healthy tissue around the tumor compared with x-ray radiation.
The study explains this phenomenon. It says protons are heavy particles that are positively charged and stop once they reach their target. X-rays are made of photons, particles with almost no mass. This lightness is a drawback, as the photons travel easily through the body, but they also travel through healthy tissue on their way out after they’ve hit their target.